Osteosarcoma of the distal femur

Case contributed by Assoc Prof Frank Gaillard

Presentation

Right knee pain.

Patient Data

Age: 17 years
Gender: Female

Knee x-ray

X-ray

The distal half of the femur is occupied and expanded with a heterogeneous mass with areas of bone formation. Posterior the periosteum is elevated (Codman's triangle). 

Bone scan

Nuclear medicine

Delayed phase bone scan image demonstrates intense uptake in the distal right femur. A single focus of increased attenuation projects just to the right of the sternum inline with the chondral cartilage of the third rib. No other suspicious lesions identified. 

MRI knee

MRI

MRI through the lesion demonstrates a soft tissue mass completely replacing the medullary cavity and extending into the adjacent soft tissues. It is low to intermediate in signal on T1 and high on T2 weighted images. 

Distribution of osteosarcomas

Diagram

Distribution of osteosarcomas. The most frequent location is around the knee. Layout and distribution: Frank Gaillard 2009, Line drawing of skeleton: Patrick Lynch 2006, Creative Common NC-SA-BY

This patient went on to have surgery and an osteosarcoma was histologically confirmed. 

Post op

X-ray

A limb sparing resection has been performed. The distal femur and adjacent tibial plateau has been resected and a total knee replacement inserted. 

Case Discussion

This case demonstrates relatively typical appearances of a bone forming osteosarcoma of the distal femur (typical location) in a 17-year-old (typical age). 

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